CA1168520A - One-piece, snap-on, foil-shaped, low-drag fairing for long underwater cables - Google Patents
One-piece, snap-on, foil-shaped, low-drag fairing for long underwater cablesInfo
- Publication number
- CA1168520A CA1168520A CA000354637A CA354637A CA1168520A CA 1168520 A CA1168520 A CA 1168520A CA 000354637 A CA000354637 A CA 000354637A CA 354637 A CA354637 A CA 354637A CA 1168520 A CA1168520 A CA 1168520A
- Authority
- CA
- Canada
- Prior art keywords
- fairing
- cable
- hollow
- tail
- fairing element
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B21/00—Tying-up; Shifting, towing, or pushing equipment; Anchoring
- B63B21/56—Towing or pushing equipment
- B63B21/66—Equipment specially adapted for towing underwater objects or vessels, e.g. fairings for tow-cables
- B63B21/663—Fairings
Abstract
ABSTRACT OF THE DISCLOSURE
A finite length, monolithic, one-piece fairing element is provided which is a snap-on, foil-shaped, element of streamlined hydro-dynamic shape, having an outer wall formed of high strength material, the fairing being symmetrical about its central longitudinal axis, and adapted to be associated with a plurality of similar such fairing elements in end-to-end abutting relation on a cable. The fairing element includes a hollow rounded nose portion within the cable is adapted to be disposed.
A spring tail portion is provided by a slit in the tail thereof along the central longitudinal axis. A hollow expandible channel is provided symmetrical about the central longitudinal axis interconnecting the spring tail portion and the hollow nose portion, and through which the cable is adapted to be urged from its entry at the tail portion to its lodging at the hollow rounded nose portion. An inner wall section made of that high-strength material is spaced from the outer wall of the substantially hollow fairing element by a plurality of ribs of that high-strength material thereby defining the hollow expandible channel and also a double wall section only along the flanks of the fairing between the nose portion and the tail portion. The fairing element thus permits easy assembly.
In addition the thin but double walled snap-on fairing element substanti-ally eliminates distortion of the side walls due to hydrodynamic flow pressure while keeping the section light.
A finite length, monolithic, one-piece fairing element is provided which is a snap-on, foil-shaped, element of streamlined hydro-dynamic shape, having an outer wall formed of high strength material, the fairing being symmetrical about its central longitudinal axis, and adapted to be associated with a plurality of similar such fairing elements in end-to-end abutting relation on a cable. The fairing element includes a hollow rounded nose portion within the cable is adapted to be disposed.
A spring tail portion is provided by a slit in the tail thereof along the central longitudinal axis. A hollow expandible channel is provided symmetrical about the central longitudinal axis interconnecting the spring tail portion and the hollow nose portion, and through which the cable is adapted to be urged from its entry at the tail portion to its lodging at the hollow rounded nose portion. An inner wall section made of that high-strength material is spaced from the outer wall of the substantially hollow fairing element by a plurality of ribs of that high-strength material thereby defining the hollow expandible channel and also a double wall section only along the flanks of the fairing between the nose portion and the tail portion. The fairing element thus permits easy assembly.
In addition the thin but double walled snap-on fairing element substanti-ally eliminates distortion of the side walls due to hydrodynamic flow pressure while keeping the section light.
Description
5 2 () This invention relates to one-piece snap-on, foil-shaped, lo~"
drag fairing element for use on long underwater cables.
When towing a submerged object, it is usually desirable that-in-duced cable vibrations and noise be suppressed and that cable drag be mini-mi~ed to achieve maximum depth for a given length of such underwater cable.
These objects have been achieved in the past by enclosing the cable with fairings of more or less streamlined shape, or, less effectively with trail-ing ribbons or hair-like material embedded in the cable.
Cable fairing generally consists of a body attached to the cable to modify the flow characteristics of the water around such cable. In the use of fairing ~lements in a towed sonar system where a cable is used to tow a submerged body behind a vessel, drag on the towing cable is reduced by fairing elements attached in stacked relation longitudinally along the cable in close abutting relation. It is necessary to wind the tow line, with the fairing attached thereon, onto a winch drum and to accomplish this the fairing must be divided into a number of individual elements. In sonar systems, problems can be encountered from winding the cable with the fairing elements thereon onto the winch drum due to the fact that the fairing elements are rigid which results in a sharp transition in the cable inter-mediate each ad~acent pair of fairing elements. A cable in a sonar systemlncludes a plurality of electrical conductors and sharp bends ultimately can result in breaking one or more conductors. When this happens, the entire cable may have to be replaced.
One such prior art fairing is provided by United States Patent No. 2,397,957 issued April 9, 1946 to H.B. Freeman. That patent alleged to provide a fairing for a cable comprising a plurality of cable-wise nor-mally aligned tail portions, and flexible means covering the tail portions and normally securing them in spaced relation each to the others and forming a head portion for embracing the cable with an easy fit. This was said 5 2 n ~o permit the fairing, and to a limited extent the separate tail portisn~, to swivel with respect to the cable.
Another such fairlng is provided in United States Patent~Jo.
drag fairing element for use on long underwater cables.
When towing a submerged object, it is usually desirable that-in-duced cable vibrations and noise be suppressed and that cable drag be mini-mi~ed to achieve maximum depth for a given length of such underwater cable.
These objects have been achieved in the past by enclosing the cable with fairings of more or less streamlined shape, or, less effectively with trail-ing ribbons or hair-like material embedded in the cable.
Cable fairing generally consists of a body attached to the cable to modify the flow characteristics of the water around such cable. In the use of fairing ~lements in a towed sonar system where a cable is used to tow a submerged body behind a vessel, drag on the towing cable is reduced by fairing elements attached in stacked relation longitudinally along the cable in close abutting relation. It is necessary to wind the tow line, with the fairing attached thereon, onto a winch drum and to accomplish this the fairing must be divided into a number of individual elements. In sonar systems, problems can be encountered from winding the cable with the fairing elements thereon onto the winch drum due to the fact that the fairing elements are rigid which results in a sharp transition in the cable inter-mediate each ad~acent pair of fairing elements. A cable in a sonar systemlncludes a plurality of electrical conductors and sharp bends ultimately can result in breaking one or more conductors. When this happens, the entire cable may have to be replaced.
One such prior art fairing is provided by United States Patent No. 2,397,957 issued April 9, 1946 to H.B. Freeman. That patent alleged to provide a fairing for a cable comprising a plurality of cable-wise nor-mally aligned tail portions, and flexible means covering the tail portions and normally securing them in spaced relation each to the others and forming a head portion for embracing the cable with an easy fit. This was said 5 2 n ~o permit the fairing, and to a limited extent the separate tail portisn~, to swivel with respect to the cable.
Another such fairlng is provided in United States Patent~Jo.
2,401,783 issued June ll, 1946 to K.H. Wilcoxon. That patent alleged to provide a cable fairing comprising a series of articulated fairing units and spring latch means. This was said to allo~
for easy releasably securing of the individual units in fairing relation to a cable.
Yet another detachable fairing assembly for use with carriers o~ sensitive instruments and the like which are towed through a fluid such as water at some distance from a towing vessel, was said to be provided in United States Patent No.
for easy releasably securing of the individual units in fairing relation to a cable.
Yet another detachable fairing assembly for use with carriers o~ sensitive instruments and the like which are towed through a fluid such as water at some distance from a towing vessel, was said to be provided in United States Patent No.
3,209,718 issued October 5, 1965 to R.L. Rather et al. That patent alleged to provide the combination with a marine tow-line assembly comprising a load-bearing line and at least one conductor external to such line, the addition of a plurality of removable fairings having two side walls embracing the ex-ternal conductor at intervals along its longitudinal axis The fairings were said to include quick-disconnect means for holding the conductor within the side walls of the fairings so as to permit longitudinal movement with respect to the load-bearing line. A plurality of quick-disconnect, snap-on clamps were said to be secured ~long the load-bearing line, such clamps were said to have at least two arcuate interconnecting pieces for embracing the load-bearing line for transmitting - the weight of the fairings and to have holding means to hold the fairings to the load-bearing line.
Still another fairing assembly with convenient snap-on charactexistics for a tow-line assembly and which could attempt to overcome the problem that vibrations established on the line 3 5 Z (~
often interfered with reliable data results transrnitted on the line by setting up false vibration patterns was said to be provided in United 5'tates Patent No. 3,241, 513 issued March 22, 1966 to X.C. Rather et al. That patent alleged to provide a marine -tow-line assembly for use in towing submeryed objects.
The assembly was said to comprise a channel member, ovoid in cross-section and having bilaterally symmetrical arcuate side walls with the opening through its apex. A line extended through the channel and was laterally removable therefrom. A fin me~ber extended from one of the side walls and in a plane approximately bisecting the apex of the channel member and was said to provide the assembly with hydrodynamic stability. Means were included releasably engaging the line within the apex opening. This was said to retain the line releasably within the channel.
A further such fairing element was provided by Canadian Patent No. 869,811 issued May 4, 1971 to F.W.W. Pfeiffer, assigned to Fleet Manufacturing Limited. That patent provided a fairing element adapted to~be associated with a plurality of such elements in end-to~end abutting relation on a tow line.
The fairing element included a rigid body having a pair of opposed longitudinal marginal edges. Means were provided for attaching the tow line or cable to the body to extend along a path intermediate the marginal edges and generally parallel thereto. A pair of opposed ends provided abutting surfaces on the adjacent elements arranged end-to-end and extending along a predetermined path. Means were provided including a portion on one end of the body cooperating with a portion on the opposite end of the body of an adjacent element permitting - adjacent elements to remain in contact during angular changes ~ J S~.~20 of adjacent elements relative to one another and located such as to minimi~e any change in pitch length adjacent a path along which the cable is disposed.
Yet another patent proposing an improved fairing element is Canadian Patent No. 872,007 issued June 1, 1971 to F.W.W.
Pfeiffer, assigned to Fleet Manufacturing Limited. That patent provided the fairing elements which had adjacent faces fully in abutting relation when the cable is in a towing condition and a resilient compressible portion on such faces to deform upon the application of higher forces, for example, when the faired cable is wound onto a winch drum. The fairing elements were attached to the cable with the cable spaced inwardly from the marginal edges and thus when the faired cable was wound onto the winch drum, there was a change in curvature of the path followed by the cable. Resilient material was interposed between at least selected portions of adjacent fairing elements allowing compression, i.e., shortening of one edge of the pitch length of fairing element.
Still another such faired cable was provided by Canadian Patent No. 877,061 issued August 3, 1971 to H.H. Loshigian.
That patent provided a faired cable having the outer cross-sectional contours of an airfoil so designed as to have its center of pressure approximately at the quarter chord position (as measured from the leading edge of the section). The forward part of the cross section was constituted by a rearwardly open channel like or substantially U-shaped relatively less flèxible strength member, this shape disposing its shear center consider-ably forward of its centroid and essentially in the immediate vicinity of the leading edge of the cable section. The aft part - of the cross section is attached to the rearwardmost end of the 1 3 ~i8520 cable part which includes the strength rnember, e.g., at the ends of the legs of the "U" or flanges of the channel, and has the form of a relatively more flexible tail of ~3ubstantiall-y triangular shape.
Still another such faired cable was provided in Canadian Patent No. 887,428 issued December 7, 1971 to H.E~. Pearce et al. That patent provided fairings which were interconnected by link means extending between and permitting relative move-ment of adjacent fairings. Each fairing included a fin member 10 of substantially symmetrical~hydrofoil cross section provided with an arcuate opening in the leading edge thereof. The opening was constructed and shaped such that the fairing could be clipped to or unclipped from the tow line. The outer surface of each fairing in the region of the leading edge was provided with guide surfaces converging towards the leading edge.
A still further such faired cable was said to be pro-vided in Canadian Patent No. 896,987 issued April 4, 1972 to N.E. Hale et al. That patent was alleged to provide a ~able fairing for assembl-y with and in substantial alignment with a 20 plurality of like cable fairings on a cable. The Eairing-included a flexible hollow nose for accomodating the cable and at least one comparatively rigid tail member, and means for joining the fairing to the next adjacent fairing of a plurality of assembled fairings.
Yet another such faired cahle is -provided in Canadian Patent No. 919,998 issued January 30, 1973 to P.B. Kénnedy. That patent was said to provide a low-drag, high-speed towing cable for towing submerged objects. The towing cable had an elongated leaaing edge member and an elongated trailing edge member assembled continuously along a plane par-allel to the towing cable elongate dimension to for~ an overallconstant hydrofoil cross-sectional shape.
Still another such faired cable was providea by Canadian Patent No. 966,015 issued April 15, 1975 to D. Toussainst et al.
That paten-t was said to provide a fairing or jacketing for under-water cables, with streamline profile. The profile was composed of two completely separable profiled strips for individual reel-ing, each having a first surface to be placed into abutment with the first surface of the respective other first strip and each having a second surface disposed symmetrically to a plane defined by the first surfaces when placed in abutment to each other. The strip each had at least one recess open to the first surface, the recesses having location and contour complementary to each other to define an elongated cavity for loosely rece~ving the rope or cable when the first surfaces are in mutual abutment.
Fastening means were provided on the strips in the first surfaces thereof for releasably interconnecting the two'strips between the cavity and the leading edge of the profile, and for releas-ably interconnecting the two strips between the cavity and the trailing edge of the profile.
Yet another fairing is provided by Canadian Patent No.
1,018,834 issued October 11, 1977 to J.A.R. Marchag et al.
Still another cable fairing was provided by Canadian Patent No. 1,045,471 issued January 2, 1979 to T.I. Silve~.
This patent provided a hydrodynamic cable fairing section com-prising a nose portion, a body portion having two side surfaces and vane means comprising a plurality of vanes connected to each side surface of said body portion The plurality of vanes was substantially parallel to each other. The nose portion had a continuous curved surface and a longitudinal through bore means 8~20 ~or receiving a cable. The body port i on extended f~om the nose po~tion and tapered from the nose portion towards a trailing edge which forms part of the body portion. Each of the vanes included flat surfaces which tapered toward the trailing edge of the body portion.
Other patents which are of interest in this respect include U . S . Pa tent Nos:
3,060,8~6 3,092,067 3,176,646 3,194,204 3,233,571 3,352,274 3,343,515 3,343,516 and 3,379,161 Nevertheless, the fairings and faired cables described above suf fer from one or more drawbacks .
More sophisticated towed naval sonar systems use fairings which are reasonably effective. The problem is that these are permanent fairings, ~hïch remain with the cable, and are wound with it on an off the hoist drum used to store the cable. As multilayer winding of the faired cable on and off the drum is virtually impossible without fairing destruction, single layer winding is obligatory. For very long cables this necessitates the use of hoist drums of enormous size, often large enough to make a towed system impractical wh~re space is at a premium, which is nearly always the case on ships. ~n addition, to keep the drum face to a minimum length, the grooving of the drum must be pitc:hed as closely as possible, and this necessitates the use of fairings with paxallel sides, which is not the most optimum shape ' for maximum drag reduction .
As noted abcve, ~ number of qllickly at~echable/detachable fair-ings have been developed in the past to overcome the proble~s described above. These fairings are attached during payout and detached during haul in outboard of the hoist drum to achieve the economy of space afforded by multilayer winding. The problem with such fairings up to now is that the quick attach/detach feature has resulted in liberties being taken with the basic fairing shape. In fact, some "snap on" fairings are of quite crude shape, and therefore are of very limited effectiveness. Hair and ribbon fairings have also been used to allow multilayer winding. They may be - 7a -~ ~ 6~520 effective in reducing vibration, but are frequently worse than no fairings at all as regards to drag reduction. In short, the more effective the fairing, the more permanent the installation; and the greater the ease of applying and detaching the fairing, the less effective the fairing has been in reducing drag.
Accordingly, objects of ~spects of the present invention include the provision of fairings which have very low drag; have low internal friction against stacking forces and cable reactions; hydrodynamic stabili-ty; are reasonably inexpensive to produce one piece construction; reason-ably light weight; have high resistance to distortion under hydrodynamicforces; are accurately reproducible in high volume production; are quickly attachable and detachable, given proper tooling, storage maga~ine and automated feeding means; and will allow multilayer spooling of long lengths of bare cable on the hoist drum. While all of the prior art fairings have one or more of the above features, none of the prior art has all of them.
By one broad aspect of this invention a finite length, mono-lithic, one piece snap-on, foil shaped, low drag fairing element of streamlined hydrodynamic shape is provided, having an outer wall formed of high strength material, the fairing being symmetrical about its central longitudinal axis, and adapted to be associated with a plurality of similar such fairing elements in end-to-end abutting relation on a cable, said fairing element comprising: a hollow rounded nose portion within which said cable is adapted to be disposed; a spring tail portion provided by a slit in the tail thereof along the central longitudinal axis; a hollow expandible channel symmetrical about said central longitudinal ....
~ J 68520 axis interconnecting the spring tail portion and the hollow nose portion, and through which the cable is adapted to be urged from its entry at the tail portion to its lodging at the hollow rounded nose portion; and an inner wall section of the high strength material spaced from the outer wall of the substantially hollow fairing element by a plurality of ribs of the high strength material, thereby defininy the hollow expandible channel and also a double wall section along the flanks sf the fairing element between the nose portion and the tail portion.
By a preferred variant thereof, a pair of opposed ends of such substantially hollow fairing element provide abutting surfaces on the mutually opposed adjacent elements when they are arranged end-to-end extending along a predetermined path, each abutting surface including a recessed end non-contact surface extending from-the tail and along the flank towards the nose short contact surfaces at, and flanking, each side of the cable; and an angularly bevelled non-contact surface at the nose to allow for cable curvature, thereby reducing friction msvement by minimizing the moment arm to the point where friction forces act.
By a variant thereof, the substantially hollow fairing element includes a pair of opposed internal engagement surfaces adjacent the hollow nose portion to retain the cable in essentially fixed loca-tion within the hollow nose portion of the fairing element.
By another variant, the double walled flank section is defined by a plurality of separate chambers provided by a plurality of longi-tudinally extending ribs inner and outer wall section interconnecting ribs.
By yet another variant, the fairing element includes a coating of a corrosion-resistant flurocarbon polymer, thereon.
~ g .~
.
.,~' f~
~ 3 ~2{) By another aspect of this invention, the combination is provided with a cable, of a plurality of substantially hollow, finite length monolithic one-piece, snap-on, foil-shaped, low drag fairing elements of streamlined hydrodynamic shape, having an outer wall formed of high strength material, the fairing ele~ent being symmetrical about its central longitudinal axis, and adapted to be associated with a plurality of similar such fairing elements in end-to-end abutting relation in a cable, each of the fairing elements comprising: a hollow rounded nose portion within which the cable is adapted to be disposed; a spring tail portion provided by a slit in the tail thereof along the central longitudinal axis; a hollow expandible channel symmetrical about the central longi tudinal axis; a hollow expandible channel symmetrical about the central longitudinal axis interconnecting the spring tail portion and the hollow nose portion, and through which the cable is adapted to be urged from its entry at the tail portion to its lodging at the hollow rounded nose portion; and an innter wall section of the high-strength material spaced from the outer wall of the substantially hollow fairing element by a plurality of ribs of the high strength material, thereby defining the hollow expandible channel and also a double wall section only along the flanks of the fairing element between the portion of the tail portion.
By a variant thereofj in the fairing element, a pair of opposed ends of the fairing element provide abutting surfaces on the mutually opposed adjacent elements when they are arranged end-to-end extending along a predetermined path, each such abutting surface including a re-cessed end non-contact surface extending from the tail and along the flank towards the nose; short contact surfaces at, and flanking, each --` 10 ~
68~2n si.de of the cable; and an angularly bevelled con-contact at the nose to allow for cable curvature, thereby reducing friction movement by minimizing the moment a,rm to the point where friction forces act.
By a variant thereof, the combination includes a plurality of thrust rings disposed periodically around the cable in addition to the fairings.
By another variant, the fairings elements include a coating of a corrosion-resi.stant flurocarbon polymer.
- 10 a -- ` 11 6852n In the accompanying drawings, Pigure 1 is a section taken through a fairing of the present invention and a cable;
Figure 2 is a longitudinal view of a cable and fairing system of an aspect of this invention;
.. ......
Figure 2a is an enlargement of a portion of a cable and fairing system of an aspect of this invention; and Figure 3 i6 a schematic view of the develop~ent of hydrodynamic pressure as fluid flows past a streamlined shape.
As seen in Figure 1, the fairing 10 is designed using a basic high lift, low-drag wing foil shape with modified nose known as NACA 0025, although other symmetric foil shapes could also be adapted for use. (NACA is an abbreviation for the National Advisory Committee for Aeronautics). This shape is distinctly better hydrodynamically than the parallel side fairings used in perm-anent installations and can be used to advantage here because there is no necessity to store the fairings on the drum The fairing 10 includes a rounded nose portion 11, a tail section 12 and a pair of flanks 13. The fairing is I :~ 6852n sprung at the tail 12 by means of a longitudinal slit 14 tnerein.
The purpose of slit 14 will be described hereinafter. ~he flanks 13 are provided as doubled walled members including an inner ~"all 15. Preferably the double walled members are provided as a plur-ality of longitudinally extending chambers 16 defined by a plur-ality of longitudinally extending ribs 17. The ribs 18 adjacentthe nose 11 provide internal engagement surfaces to aid in retain-ing the cable 20 in place.
For light weight combined with stiffness the preferred ; material of construction of the fairing is a high-strength aluminum alloy closed extrusion, wherefrom the individual fairings can be parted off in convenient lengths of say one foot each.
The tail 12 of the fairing 10 is slit open at 14 to allow insertion of installation tooling. One method involves the use of a spreader bar 21 as shown in chain dotted lines in Figure 1. This spreader bar 21 would be used to pry apart the tail 12, one corner of the spread fairing 10 would be slipped over the cable 20, the spreader bar 21 then removed, and then the entire fairing 10 would be snapped over the cable 20 with furLher assistance ~rom the spreader bar. No links interconnecting adjacent fairings ~re required. On detaching the ~airings 10, the spreader bar 21 would again be inserted into the tail slit 14, the fair-ing 10 removed until the cable 20 hits the tip of the spreader bar 21, the spreader bar 21 then removed and the fairing 10 would then be snapped off the cable 20.
1 } 685~) As 5~ in Figure 2, tl~ irir,y. 10 are o7i .,. ' . _ d on t:le cable 20. If the cable is inclined to the flo~", a portion of the drag acts to push the fairing down the cable. When allo~,/ea to accumulate over an entire cable length, this "stacking" force can reach truly large proportions, and has been known to darnage or destroy fairings at the lower reaches or distal end of the cable. It is now becoming commonplace to relieve these stacking forces by installing thrust rings seen as rings 22 in Figure 2 ~called "anti- stacking rings") periodically around the cable 20. In this manner, stacking forces can only build up over a section of fairings 20 between two adjacent rings 22, and will not be transmitted to the next section of fairings 20. Never-theless, even small stacking forces may be large enough through the action of friction between adjacent fairings, when coupled with friction between the cable and fairing nose, to create friotion moments which will prevent lifting forces from straight-ening out a misaligned fairing. A misaligned fairing acts as a rudder to produce cable tow-off. This effect can be alleviated by two means. The first is to cut the fairing ends as shown in Figure 2. As seen in Figure 2, the fairings 10 have their ends cut as follows. A shallow recess 23 is cut into the ends of the fairings aft of cable 20 to prevent contact in that zone with adjacent fairings.
Short contact surfaces 24 are provided on the fair~ng ends at and ~flanking each side of the cable. At the forward portion of the nose 11, a bevelled section 25 is provided to allow cable flexure. This structure will reduce the friction mo~ent by minimizing the moment art to the point where frictlon forces act.
~ ; The secon~d means is to coat the entire fairing 10 with a corrosion-resistant, baked-on, dry-lubricant fluorocarbon coating (not shown). This will reduce the friction moment by reducing the coefficient of friction and thus the friction force.
- 12 ~
" ~ J 6 8 t, ~ () It will also increase the corrsion resistance of the fairing, and is a preferred embodiment of this invention.
In a preferred variant of the fairing of an aspect oE
this invention, most of the flanks 13 of the fairings 10 are reinforced with a double wall 15. The reason for this can be deduced from Figure 3, which is taken from the results of model tests done by the National Research Council on domes of similar shape many years ago. When a fluid flows past a streamlined shape tor conversely, when such a shape moves in a stationary fluid), a concentrated zone oE high pressure A builds up at the nose "~". This "stagnation pressure" is inward, and is e~ual to 1/2 pV2, where p = mass density of the fluid and V
is speed. In the case of a fairing, this pressure is resisted ~ U6 Clql~6 h ~ by cable reaction from ca~ A. This is followed by a negative pressure "~" on the forward flanks tending to force them apart and a much smaller positive pressure "D" on the trailin~ section.
The net result on a fairing split at the tail would be that the flanks would be deflected outward as a cantilever beam "built in" at the nose. In an unreinforced split fairing, this deflec-tion may easily be so large at high speeds as to distort thebasic fairing shape so badly that its primary function as a drag reducer is destroyed. The use of double walls 15 thus serves to introduce reinforcement to 'the flanks to limit hydro-dynamic outward deflection to only thousandths of an inch.
Still another fairing assembly with convenient snap-on charactexistics for a tow-line assembly and which could attempt to overcome the problem that vibrations established on the line 3 5 Z (~
often interfered with reliable data results transrnitted on the line by setting up false vibration patterns was said to be provided in United 5'tates Patent No. 3,241, 513 issued March 22, 1966 to X.C. Rather et al. That patent alleged to provide a marine -tow-line assembly for use in towing submeryed objects.
The assembly was said to comprise a channel member, ovoid in cross-section and having bilaterally symmetrical arcuate side walls with the opening through its apex. A line extended through the channel and was laterally removable therefrom. A fin me~ber extended from one of the side walls and in a plane approximately bisecting the apex of the channel member and was said to provide the assembly with hydrodynamic stability. Means were included releasably engaging the line within the apex opening. This was said to retain the line releasably within the channel.
A further such fairing element was provided by Canadian Patent No. 869,811 issued May 4, 1971 to F.W.W. Pfeiffer, assigned to Fleet Manufacturing Limited. That patent provided a fairing element adapted to~be associated with a plurality of such elements in end-to~end abutting relation on a tow line.
The fairing element included a rigid body having a pair of opposed longitudinal marginal edges. Means were provided for attaching the tow line or cable to the body to extend along a path intermediate the marginal edges and generally parallel thereto. A pair of opposed ends provided abutting surfaces on the adjacent elements arranged end-to-end and extending along a predetermined path. Means were provided including a portion on one end of the body cooperating with a portion on the opposite end of the body of an adjacent element permitting - adjacent elements to remain in contact during angular changes ~ J S~.~20 of adjacent elements relative to one another and located such as to minimi~e any change in pitch length adjacent a path along which the cable is disposed.
Yet another patent proposing an improved fairing element is Canadian Patent No. 872,007 issued June 1, 1971 to F.W.W.
Pfeiffer, assigned to Fleet Manufacturing Limited. That patent provided the fairing elements which had adjacent faces fully in abutting relation when the cable is in a towing condition and a resilient compressible portion on such faces to deform upon the application of higher forces, for example, when the faired cable is wound onto a winch drum. The fairing elements were attached to the cable with the cable spaced inwardly from the marginal edges and thus when the faired cable was wound onto the winch drum, there was a change in curvature of the path followed by the cable. Resilient material was interposed between at least selected portions of adjacent fairing elements allowing compression, i.e., shortening of one edge of the pitch length of fairing element.
Still another such faired cable was provided by Canadian Patent No. 877,061 issued August 3, 1971 to H.H. Loshigian.
That patent provided a faired cable having the outer cross-sectional contours of an airfoil so designed as to have its center of pressure approximately at the quarter chord position (as measured from the leading edge of the section). The forward part of the cross section was constituted by a rearwardly open channel like or substantially U-shaped relatively less flèxible strength member, this shape disposing its shear center consider-ably forward of its centroid and essentially in the immediate vicinity of the leading edge of the cable section. The aft part - of the cross section is attached to the rearwardmost end of the 1 3 ~i8520 cable part which includes the strength rnember, e.g., at the ends of the legs of the "U" or flanges of the channel, and has the form of a relatively more flexible tail of ~3ubstantiall-y triangular shape.
Still another such faired cable was provided in Canadian Patent No. 887,428 issued December 7, 1971 to H.E~. Pearce et al. That patent provided fairings which were interconnected by link means extending between and permitting relative move-ment of adjacent fairings. Each fairing included a fin member 10 of substantially symmetrical~hydrofoil cross section provided with an arcuate opening in the leading edge thereof. The opening was constructed and shaped such that the fairing could be clipped to or unclipped from the tow line. The outer surface of each fairing in the region of the leading edge was provided with guide surfaces converging towards the leading edge.
A still further such faired cable was said to be pro-vided in Canadian Patent No. 896,987 issued April 4, 1972 to N.E. Hale et al. That patent was alleged to provide a ~able fairing for assembl-y with and in substantial alignment with a 20 plurality of like cable fairings on a cable. The Eairing-included a flexible hollow nose for accomodating the cable and at least one comparatively rigid tail member, and means for joining the fairing to the next adjacent fairing of a plurality of assembled fairings.
Yet another such faired cahle is -provided in Canadian Patent No. 919,998 issued January 30, 1973 to P.B. Kénnedy. That patent was said to provide a low-drag, high-speed towing cable for towing submerged objects. The towing cable had an elongated leaaing edge member and an elongated trailing edge member assembled continuously along a plane par-allel to the towing cable elongate dimension to for~ an overallconstant hydrofoil cross-sectional shape.
Still another such faired cable was providea by Canadian Patent No. 966,015 issued April 15, 1975 to D. Toussainst et al.
That paten-t was said to provide a fairing or jacketing for under-water cables, with streamline profile. The profile was composed of two completely separable profiled strips for individual reel-ing, each having a first surface to be placed into abutment with the first surface of the respective other first strip and each having a second surface disposed symmetrically to a plane defined by the first surfaces when placed in abutment to each other. The strip each had at least one recess open to the first surface, the recesses having location and contour complementary to each other to define an elongated cavity for loosely rece~ving the rope or cable when the first surfaces are in mutual abutment.
Fastening means were provided on the strips in the first surfaces thereof for releasably interconnecting the two'strips between the cavity and the leading edge of the profile, and for releas-ably interconnecting the two strips between the cavity and the trailing edge of the profile.
Yet another fairing is provided by Canadian Patent No.
1,018,834 issued October 11, 1977 to J.A.R. Marchag et al.
Still another cable fairing was provided by Canadian Patent No. 1,045,471 issued January 2, 1979 to T.I. Silve~.
This patent provided a hydrodynamic cable fairing section com-prising a nose portion, a body portion having two side surfaces and vane means comprising a plurality of vanes connected to each side surface of said body portion The plurality of vanes was substantially parallel to each other. The nose portion had a continuous curved surface and a longitudinal through bore means 8~20 ~or receiving a cable. The body port i on extended f~om the nose po~tion and tapered from the nose portion towards a trailing edge which forms part of the body portion. Each of the vanes included flat surfaces which tapered toward the trailing edge of the body portion.
Other patents which are of interest in this respect include U . S . Pa tent Nos:
3,060,8~6 3,092,067 3,176,646 3,194,204 3,233,571 3,352,274 3,343,515 3,343,516 and 3,379,161 Nevertheless, the fairings and faired cables described above suf fer from one or more drawbacks .
More sophisticated towed naval sonar systems use fairings which are reasonably effective. The problem is that these are permanent fairings, ~hïch remain with the cable, and are wound with it on an off the hoist drum used to store the cable. As multilayer winding of the faired cable on and off the drum is virtually impossible without fairing destruction, single layer winding is obligatory. For very long cables this necessitates the use of hoist drums of enormous size, often large enough to make a towed system impractical wh~re space is at a premium, which is nearly always the case on ships. ~n addition, to keep the drum face to a minimum length, the grooving of the drum must be pitc:hed as closely as possible, and this necessitates the use of fairings with paxallel sides, which is not the most optimum shape ' for maximum drag reduction .
As noted abcve, ~ number of qllickly at~echable/detachable fair-ings have been developed in the past to overcome the proble~s described above. These fairings are attached during payout and detached during haul in outboard of the hoist drum to achieve the economy of space afforded by multilayer winding. The problem with such fairings up to now is that the quick attach/detach feature has resulted in liberties being taken with the basic fairing shape. In fact, some "snap on" fairings are of quite crude shape, and therefore are of very limited effectiveness. Hair and ribbon fairings have also been used to allow multilayer winding. They may be - 7a -~ ~ 6~520 effective in reducing vibration, but are frequently worse than no fairings at all as regards to drag reduction. In short, the more effective the fairing, the more permanent the installation; and the greater the ease of applying and detaching the fairing, the less effective the fairing has been in reducing drag.
Accordingly, objects of ~spects of the present invention include the provision of fairings which have very low drag; have low internal friction against stacking forces and cable reactions; hydrodynamic stabili-ty; are reasonably inexpensive to produce one piece construction; reason-ably light weight; have high resistance to distortion under hydrodynamicforces; are accurately reproducible in high volume production; are quickly attachable and detachable, given proper tooling, storage maga~ine and automated feeding means; and will allow multilayer spooling of long lengths of bare cable on the hoist drum. While all of the prior art fairings have one or more of the above features, none of the prior art has all of them.
By one broad aspect of this invention a finite length, mono-lithic, one piece snap-on, foil shaped, low drag fairing element of streamlined hydrodynamic shape is provided, having an outer wall formed of high strength material, the fairing being symmetrical about its central longitudinal axis, and adapted to be associated with a plurality of similar such fairing elements in end-to-end abutting relation on a cable, said fairing element comprising: a hollow rounded nose portion within which said cable is adapted to be disposed; a spring tail portion provided by a slit in the tail thereof along the central longitudinal axis; a hollow expandible channel symmetrical about said central longitudinal ....
~ J 68520 axis interconnecting the spring tail portion and the hollow nose portion, and through which the cable is adapted to be urged from its entry at the tail portion to its lodging at the hollow rounded nose portion; and an inner wall section of the high strength material spaced from the outer wall of the substantially hollow fairing element by a plurality of ribs of the high strength material, thereby defininy the hollow expandible channel and also a double wall section along the flanks sf the fairing element between the nose portion and the tail portion.
By a preferred variant thereof, a pair of opposed ends of such substantially hollow fairing element provide abutting surfaces on the mutually opposed adjacent elements when they are arranged end-to-end extending along a predetermined path, each abutting surface including a recessed end non-contact surface extending from-the tail and along the flank towards the nose short contact surfaces at, and flanking, each side of the cable; and an angularly bevelled non-contact surface at the nose to allow for cable curvature, thereby reducing friction msvement by minimizing the moment arm to the point where friction forces act.
By a variant thereof, the substantially hollow fairing element includes a pair of opposed internal engagement surfaces adjacent the hollow nose portion to retain the cable in essentially fixed loca-tion within the hollow nose portion of the fairing element.
By another variant, the double walled flank section is defined by a plurality of separate chambers provided by a plurality of longi-tudinally extending ribs inner and outer wall section interconnecting ribs.
By yet another variant, the fairing element includes a coating of a corrosion-resistant flurocarbon polymer, thereon.
~ g .~
.
.,~' f~
~ 3 ~2{) By another aspect of this invention, the combination is provided with a cable, of a plurality of substantially hollow, finite length monolithic one-piece, snap-on, foil-shaped, low drag fairing elements of streamlined hydrodynamic shape, having an outer wall formed of high strength material, the fairing ele~ent being symmetrical about its central longitudinal axis, and adapted to be associated with a plurality of similar such fairing elements in end-to-end abutting relation in a cable, each of the fairing elements comprising: a hollow rounded nose portion within which the cable is adapted to be disposed; a spring tail portion provided by a slit in the tail thereof along the central longitudinal axis; a hollow expandible channel symmetrical about the central longi tudinal axis; a hollow expandible channel symmetrical about the central longitudinal axis interconnecting the spring tail portion and the hollow nose portion, and through which the cable is adapted to be urged from its entry at the tail portion to its lodging at the hollow rounded nose portion; and an innter wall section of the high-strength material spaced from the outer wall of the substantially hollow fairing element by a plurality of ribs of the high strength material, thereby defining the hollow expandible channel and also a double wall section only along the flanks of the fairing element between the portion of the tail portion.
By a variant thereofj in the fairing element, a pair of opposed ends of the fairing element provide abutting surfaces on the mutually opposed adjacent elements when they are arranged end-to-end extending along a predetermined path, each such abutting surface including a re-cessed end non-contact surface extending from the tail and along the flank towards the nose; short contact surfaces at, and flanking, each --` 10 ~
68~2n si.de of the cable; and an angularly bevelled con-contact at the nose to allow for cable curvature, thereby reducing friction movement by minimizing the moment a,rm to the point where friction forces act.
By a variant thereof, the combination includes a plurality of thrust rings disposed periodically around the cable in addition to the fairings.
By another variant, the fairings elements include a coating of a corrosion-resi.stant flurocarbon polymer.
- 10 a -- ` 11 6852n In the accompanying drawings, Pigure 1 is a section taken through a fairing of the present invention and a cable;
Figure 2 is a longitudinal view of a cable and fairing system of an aspect of this invention;
.. ......
Figure 2a is an enlargement of a portion of a cable and fairing system of an aspect of this invention; and Figure 3 i6 a schematic view of the develop~ent of hydrodynamic pressure as fluid flows past a streamlined shape.
As seen in Figure 1, the fairing 10 is designed using a basic high lift, low-drag wing foil shape with modified nose known as NACA 0025, although other symmetric foil shapes could also be adapted for use. (NACA is an abbreviation for the National Advisory Committee for Aeronautics). This shape is distinctly better hydrodynamically than the parallel side fairings used in perm-anent installations and can be used to advantage here because there is no necessity to store the fairings on the drum The fairing 10 includes a rounded nose portion 11, a tail section 12 and a pair of flanks 13. The fairing is I :~ 6852n sprung at the tail 12 by means of a longitudinal slit 14 tnerein.
The purpose of slit 14 will be described hereinafter. ~he flanks 13 are provided as doubled walled members including an inner ~"all 15. Preferably the double walled members are provided as a plur-ality of longitudinally extending chambers 16 defined by a plur-ality of longitudinally extending ribs 17. The ribs 18 adjacentthe nose 11 provide internal engagement surfaces to aid in retain-ing the cable 20 in place.
For light weight combined with stiffness the preferred ; material of construction of the fairing is a high-strength aluminum alloy closed extrusion, wherefrom the individual fairings can be parted off in convenient lengths of say one foot each.
The tail 12 of the fairing 10 is slit open at 14 to allow insertion of installation tooling. One method involves the use of a spreader bar 21 as shown in chain dotted lines in Figure 1. This spreader bar 21 would be used to pry apart the tail 12, one corner of the spread fairing 10 would be slipped over the cable 20, the spreader bar 21 then removed, and then the entire fairing 10 would be snapped over the cable 20 with furLher assistance ~rom the spreader bar. No links interconnecting adjacent fairings ~re required. On detaching the ~airings 10, the spreader bar 21 would again be inserted into the tail slit 14, the fair-ing 10 removed until the cable 20 hits the tip of the spreader bar 21, the spreader bar 21 then removed and the fairing 10 would then be snapped off the cable 20.
1 } 685~) As 5~ in Figure 2, tl~ irir,y. 10 are o7i .,. ' . _ d on t:le cable 20. If the cable is inclined to the flo~", a portion of the drag acts to push the fairing down the cable. When allo~,/ea to accumulate over an entire cable length, this "stacking" force can reach truly large proportions, and has been known to darnage or destroy fairings at the lower reaches or distal end of the cable. It is now becoming commonplace to relieve these stacking forces by installing thrust rings seen as rings 22 in Figure 2 ~called "anti- stacking rings") periodically around the cable 20. In this manner, stacking forces can only build up over a section of fairings 20 between two adjacent rings 22, and will not be transmitted to the next section of fairings 20. Never-theless, even small stacking forces may be large enough through the action of friction between adjacent fairings, when coupled with friction between the cable and fairing nose, to create friotion moments which will prevent lifting forces from straight-ening out a misaligned fairing. A misaligned fairing acts as a rudder to produce cable tow-off. This effect can be alleviated by two means. The first is to cut the fairing ends as shown in Figure 2. As seen in Figure 2, the fairings 10 have their ends cut as follows. A shallow recess 23 is cut into the ends of the fairings aft of cable 20 to prevent contact in that zone with adjacent fairings.
Short contact surfaces 24 are provided on the fair~ng ends at and ~flanking each side of the cable. At the forward portion of the nose 11, a bevelled section 25 is provided to allow cable flexure. This structure will reduce the friction mo~ent by minimizing the moment art to the point where frictlon forces act.
~ ; The secon~d means is to coat the entire fairing 10 with a corrosion-resistant, baked-on, dry-lubricant fluorocarbon coating (not shown). This will reduce the friction moment by reducing the coefficient of friction and thus the friction force.
- 12 ~
" ~ J 6 8 t, ~ () It will also increase the corrsion resistance of the fairing, and is a preferred embodiment of this invention.
In a preferred variant of the fairing of an aspect oE
this invention, most of the flanks 13 of the fairings 10 are reinforced with a double wall 15. The reason for this can be deduced from Figure 3, which is taken from the results of model tests done by the National Research Council on domes of similar shape many years ago. When a fluid flows past a streamlined shape tor conversely, when such a shape moves in a stationary fluid), a concentrated zone oE high pressure A builds up at the nose "~". This "stagnation pressure" is inward, and is e~ual to 1/2 pV2, where p = mass density of the fluid and V
is speed. In the case of a fairing, this pressure is resisted ~ U6 Clql~6 h ~ by cable reaction from ca~ A. This is followed by a negative pressure "~" on the forward flanks tending to force them apart and a much smaller positive pressure "D" on the trailin~ section.
The net result on a fairing split at the tail would be that the flanks would be deflected outward as a cantilever beam "built in" at the nose. In an unreinforced split fairing, this deflec-tion may easily be so large at high speeds as to distort thebasic fairing shape so badly that its primary function as a drag reducer is destroyed. The use of double walls 15 thus serves to introduce reinforcement to 'the flanks to limit hydro-dynamic outward deflection to only thousandths of an inch.
Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A finite length monolithic one-piece, snap-on, foil-shaped low drag fairing element of streamlined hydrodynamic shape, having an outer wall formed of high strength material, the fairing being symmetrical about its central longitudinal axis, and adapted to be associated with a plurality of similar such fairing elements in end-to-end abutting relation on a cable, said fairing element comprising: a hollow rounded nose portion within which said cable is adapted to be disposed; a spring tail portion provided by a slit in the tail thereof along the central longitudinal axis; a hollow expandible channel symmetrical about said central longi-tudinal axis interconnecting said spring tail portion and said hollow nose portion, and through which said cable is adapted to be urged from its entry at said tail portion to its lodging at said hollow rounded nose portion; and an inner wall section of said high strength material spaced from said outer wall of said substantially hollow fairing element by a plurality of ribs of said high strength material, thereby defining said hollow expandible channel and also a double wall section along the flanks of said fairing element between said nose portion and said tail portion.
2. The substantially hollow monolithic fairing element of claim 1 wherein a pair of opposed ends of said fairing provide abutting surfaces on the mutually opposed adjacent elements when they are arranged end-to-end extending along a predetermined path, each said abutting surface ex-tending from said tail and said flank towards said nose; short contact surfaces at, and flanking, each side of said cable; and an angularly bevelled non-contact surface at said nose to allow for cable curvature, thereby reducing friction moment by minimizing the moment arm to the point where friction forces act.
3. The substantially hollow monolithic fairing element of claim 1 including a pair of opposed internal engagement surfaces adjacent said hollow nose portion of said fairing element.
4. The substantially hollow monolithic fairing element of claim 1 wherein said double walled flank section is defined by a plurality of separate chambers provided by a plurality of longitudinally extending ribs extending between said upper wall and said outerwall, said ribs being so disposed as to be parallel to said cable.
5. The substantially hollow fairing element of claims 1 or 2 including a coating of a corrosion-resistant flurocarbon polymer.
6. In combination with a cable, a plurality of substantially hollow, finite length monolithic one-piece, snap-on, foil-shaped, low drag fairing elements of streamlined hydrodynamic shape, having an outer wall formed of high strength material, the fairing element being symmetri-cal about its central longitudinal axis, and adapted to be associated with a plurality of similar such fairing elements in end-to-end abutting relation in a cable, each of said fairing elements comprising: a hollow rounded nose portion within which said cable is adapted to be disposed;
a spring tail portion provided by a slit in said tail thereof along said central longitudinal axis; a hollow expandible channel symmetrical about said central longitudinal axis interconnecting said spring tail portion and said hollow nose portion, and through which said cable is adapted to be urged from its entry at said tail portion to its lodging at said hollow rounded nose portion; and an inner wall section of said high strength material spaced from said outer wall of said substantially hollow fairing element by a plurality of ribs of said high strength material, thereby defining said hollow expandible channel and also a double wall section only along said flanks of said fairing element between said portion and said tail portion.
a spring tail portion provided by a slit in said tail thereof along said central longitudinal axis; a hollow expandible channel symmetrical about said central longitudinal axis interconnecting said spring tail portion and said hollow nose portion, and through which said cable is adapted to be urged from its entry at said tail portion to its lodging at said hollow rounded nose portion; and an inner wall section of said high strength material spaced from said outer wall of said substantially hollow fairing element by a plurality of ribs of said high strength material, thereby defining said hollow expandible channel and also a double wall section only along said flanks of said fairing element between said portion and said tail portion.
7. The combination of claim 6 including a plurality of thrust rings disposed periodically around the cable in addition to said fairing elements.
8. The combination of claim 6 wherein a pair of opposed ends of said substantially hollow fairing elements provide abutting surfaces on the mutually opposed adjacent elements when they are arranged end-to-end extend-ing along a predetermined path, each said abutting surface including a re-cessed end non-contact surface extending from the tail and along the flank towards the nose; short contact surfaces at, and flanking, each side of the cable; and an angularly bevelled non-contact surface at the nose to allow for cable curvature, thereby reducing friction moment by minimizing the moment arm to the point where friction forces act.
9. The combination of claim 6 including a coating of a corrosion-resistant flurocarbon polymer on said fairing elements.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000354637A CA1168520A (en) | 1980-06-23 | 1980-06-23 | One-piece, snap-on, foil-shaped, low-drag fairing for long underwater cables |
| US06/270,881 US4365574A (en) | 1980-06-23 | 1981-06-05 | One-piece snap-on foil-shaped low-drag fairing for long underwater cables |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000354637A CA1168520A (en) | 1980-06-23 | 1980-06-23 | One-piece, snap-on, foil-shaped, low-drag fairing for long underwater cables |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1168520A true CA1168520A (en) | 1984-06-05 |
Family
ID=4117246
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000354637A Expired CA1168520A (en) | 1980-06-23 | 1980-06-23 | One-piece, snap-on, foil-shaped, low-drag fairing for long underwater cables |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4365574A (en) |
| CA (1) | CA1168520A (en) |
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| JPS61500112A (en) * | 1983-09-13 | 1986-01-23 | ユニバ−シテイ オブ バス | streamlined structure |
| GB2162610B (en) * | 1984-08-02 | 1987-12-16 | Thomas Henderson | Regulation of response of bodies to a fluid flow |
| MY101148A (en) * | 1986-02-28 | 1991-07-31 | Shell Int Research | Apparatus for towing a pipestring at a controlled depth through a body of water |
| US4829929A (en) * | 1987-11-02 | 1989-05-16 | Kerfoot Branch P | Fluid-flow drag reducers |
| US5335620A (en) * | 1993-03-31 | 1994-08-09 | The United States Of America As Represented By The Secretary Of The Navy | Protective fairing for underwater sensor line array |
| US6179524B1 (en) * | 1996-11-15 | 2001-01-30 | Shell Oil Company | Staggered fairing system for suppressing vortex-induced-vibration |
| US6401646B1 (en) * | 2000-09-14 | 2002-06-11 | Aims International, Inc. | Snap-on rotating reduction fairing |
| US6634273B2 (en) * | 2001-05-15 | 2003-10-21 | Edo Corporation | Open loop minesweeping system |
| US20060006287A1 (en) * | 2004-01-16 | 2006-01-12 | Ferguson Stanley D | Fairing and airfoil apparatus and method |
| US7967252B2 (en) * | 2004-01-16 | 2011-06-28 | The Boeing Company | Fairing and airfoil apparatus and method |
| US7967253B2 (en) * | 2004-01-16 | 2011-06-28 | The Boeing Company | Antenna fairing and method |
| US7337742B1 (en) * | 2006-08-09 | 2008-03-04 | Viv Suppression, Inc. | Twin fin fairing |
| USRE48123E1 (en) | 2006-08-09 | 2020-07-28 | Asset Integrity Management Solutions, L.L.C. | Twin fin fairing |
| GB2442003A (en) * | 2006-09-21 | 2008-03-26 | Trelleborg Crp Ltd | Fairing for a marine riser |
| US8170988B2 (en) * | 2008-04-17 | 2012-05-01 | The Boeing Company | System and method for synchronizing databases |
| US8437906B2 (en) | 2008-04-17 | 2013-05-07 | The Boeing Company | System and method for generating maintenance release information |
| ITTO20090008U1 (en) | 2009-01-23 | 2010-07-24 | Massimo Ippolito | ROPE FOR TROPOSFERIC WIND GENERATOR. |
| US8511245B2 (en) * | 2011-05-16 | 2013-08-20 | VIV Solutions LLC | Helical strake systems |
| NO20120781A1 (en) * | 2011-07-14 | 2013-01-15 | Cggveritas Services Sa | Clingy outer covering and method |
| GB2492889A (en) * | 2011-07-14 | 2013-01-16 | Cgg Veritas Services Sa | Clamp on seismic cable fairing |
| US9632195B2 (en) * | 2011-10-28 | 2017-04-25 | Gx Technology Canada Ltd. | Steerable fairing string |
| CN102434546A (en) * | 2011-12-09 | 2012-05-02 | 中国船舶重工集团公司第七一五研究所 | Guide streamer |
| US8826842B2 (en) | 2012-02-23 | 2014-09-09 | Pgs Geophysical As | Method and system of a marine fairing |
| US9869128B1 (en) | 2012-11-24 | 2018-01-16 | VIV Solutions LLC | Installation systems and methodology for helical strake fins |
| US9453319B2 (en) | 2013-10-08 | 2016-09-27 | Applied University Research, Inc. | Scour preventing apparatus for hydraulics structures |
| EP3227174B1 (en) * | 2014-12-05 | 2019-08-28 | GX Technology Canada Ltd. | Segmented-foil divertor |
| US10865910B1 (en) | 2015-04-17 | 2020-12-15 | VIV Solutions LLC | Coupled fairing systems |
| AU2016337528B2 (en) | 2015-10-15 | 2020-11-12 | Ion Geophysical Corporation | Dynamically controlled foil systems and methods |
| MX2018009866A (en) | 2016-02-16 | 2018-11-09 | Gx Tech Canada Ltd | Ribbon foil depressor. |
| US10337649B1 (en) | 2016-03-02 | 2019-07-02 | VIV Solutions LLC | Strake system |
| US10473131B1 (en) | 2016-07-10 | 2019-11-12 | VIV Solutions LLC | Helical strakes and collar |
| US10293915B2 (en) | 2016-12-13 | 2019-05-21 | The Boeing Company | Apparatuses and methods for aerodynamic window assemblies |
| US11261675B2 (en) | 2018-01-16 | 2022-03-01 | VIV Solutions LLC | Methods for constructing a helical strake segment using one or more shell sections and fins |
| MX2021003909A (en) | 2018-10-09 | 2021-06-04 | Gx Tech Canada Ltd | Modular foil system for towed marine array. |
| US11427285B2 (en) * | 2018-12-19 | 2022-08-30 | Pgs Geophysical As | Slit fairing for towed marine equipment |
| CN110515118B (en) * | 2019-09-25 | 2020-11-20 | 大连理工大学 | Hydrophone air guide sleeve device used in deep sea environment |
| CN111188815B (en) * | 2020-02-08 | 2021-11-23 | 西南石油大学 | Vibration suppression device and method for major-headed fish-shaped slotted flow guide injection and tail swinging |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3352118A (en) * | 1965-08-11 | 1967-11-14 | Exxon Production Research Co | Frictional drag reducer for immersed bodies |
| CA869811A (en) * | 1968-07-04 | 1971-05-04 | W. W. Pfeiffer Frank | Fairing element |
| US3712261A (en) * | 1971-04-01 | 1973-01-23 | Ocean Science & Eng | Fairing |
| CA1059841A (en) * | 1976-10-08 | 1979-08-07 | Neville E. Hale | Fairing for pipes |
-
1980
- 1980-06-23 CA CA000354637A patent/CA1168520A/en not_active Expired
-
1981
- 1981-06-05 US US06/270,881 patent/US4365574A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| US4365574A (en) | 1982-12-28 |
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